A Civil GPS Anti-Spoofing and Recovering Method Using Multiple Tracking Loops and an Adaptive Filter Technique

摘要

Nowadays, the majority of location based services(LBS) rely on a GPS receiver to determine a mobile userposition.[1] Though the GPS give a suitable accuracy ofposition determination and stable measurements in mostcases, still the GPS signal from the satellites is too weakto be influenced by signal interferences in the samefrequency band or several harmonics. Above all, theintended signal interferences such as the jamming and thespoofing may threaten a security of the civil GPS whichuse L1 C/A code for positioning.[2] From among these,the spoofing attack is more menacing since the spoofingattack may lead the GPS receiver to the intendedtrajectory. In addition, it is known that the GPS L1 C/Areceiver can be deceived by a high powered pseudo GPSsignal which is within a range of 1 chip in code phase andabout 300 Hz of Doppler frequency error to the authenticGPS signal.[3] This paper presents a conceptual systemstructure for the GPS anti-spoofing method including arecovering of the authentic GPS signal after the spoofingattack succeeded. This facility can be achieved by usingmultiple tracking loops and a feedback structure ofadaptive filter technique to estimate both the authenticGPS signal and the spoofed GPS signal. In the proposedmethod, the estimation of each tracking loop is used toestimate the signal in the other tracking loop. In this paper,the system structure for the proposed method is presented,and a simulation to certify the possibility of the method iscarried out.